Smoke detection systems in aircraft cargo compartments have historically experienced a high incidence of false alarm rates. Some smoke detection systems used in aircraft cargo compartments consist of a network of “spot-type” smoke detectors coupled with an alarm system. The network of detectors sends alarm status signals to the alarm system, which provides a warning signal to the flight deck, where a decision may take place to initiate fire suppression and other safety systems. Other proposed smoke detection systems may employ video cameras.
The existence of “particulates” such as mist, dust, condensation, oil droplets and other aerosols in the cargo hold compartments and the sensitivity of current sensor systems contribute to the “high” false alarm rates. In some cases, the ratio of false to genuine alarms may reach 200:1. One study of verified smoke events vs. total alarms indicates that over 90% of all alarms are false due to these particulates. The direct cost of each false alarm may exceed $50,000 and may include indirect consequences such as (1) increased safety risk due to forced landings at unfamiliar or less adequate airports, (2) loss of confidence in detection systems, and (3) risk of injury to passengers and crewmembers during evacuation.
Accordingly, a need exists in the art for improved techniques for smoke and fire hazard detection and evaluation.